Field
The described technology relates generally to an organic light emitting diode (OLED) display and a manufacturing method thereof.
Description of the Related Technology
An organic light emitting diode display includes two electrodes and an organic emission layer interposed therebetween, electrons injected from a cathode that is one electrode and holes injected from an anode that is another electrode are bonded to each other in the organic emission layer to form an exciton, and light is emitted while the exciton discharges energy.
An example of a method for forming an organic emission layer in such an organic light emitting diode display to display full colors is laser induced thermal imaging (LITI).
In the laser induced thermal imaging method, a laser beam generated from a laser beam generator is patterned using a mask pattern, and the patterned laser beam is irradiated onto a donor film including a base film and a transfer layer to expand part of the transfer layer and transfer it to the organic light emitting diode display, thus forming an organic emission layer on the organic light emitting diode display. Thus, this method has advantages that each emission layer can be finely patterned and dry etching can be used.
The transfer layer is made of a single layer of the organic emission layer or a dual layer of the organic emission layer and a resonance assistance layer, and when the transfer layer is made of the single layer of the organic emission layer, thermal energy is transmitted to a hole transport layer (HTL) in the laser induced thermal imaging process such that a carrier accumulation is generated in an interface between the hole transport layer (HTL) and the organic emission layer, and thereby a characteristic of the organic light emitting element may be deteriorated.
Also, when the transfer layer is made of the dual layer of the organic emission layer and the resonance assistance layer, performance of the interface between the resonance assistance layer and the organic emission layer is improved, however the carrier accumulation is generated in the interface between the hole transport layer (HTL) and the organic emission layer such that the characteristic of the organic light emitting element may be deteriorated.
Further, thermal damage to the resonance assistance layer and the hole transport layer (HTL) is serious because of the thermal energy generated when using the laser induced thermal imaging such that the driving voltage may be excessively increased.
In addition, when using the laser induced thermal imaging, heat is transmitted to the anode such that the interface characteristic between the anode and the hole injection layer (HIL) may be deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.